1. Field of the Invention
The present invention relates to processing, monitoring and display of signals, and particularly to the processing, monitoring and display of electrophysiological signals. More particularly, the present invention relates to the processing, monitoring and display of electroencephalography (EEG) signals representing cortical/brain activity. Further, the present invention relates to a method and apparatus for displaying separate electrophysiological signals and quantitative process parameters based on these signals and representing the cortical or brain activity of each of the subject's brain hemispheres on the same screen, simultaneously. Even further, the present invention, while displaying cortical or brain activity signals, relates to methods for measuring signal quality, detecting neuropathological activity in the subject, and detecting changes in subject's status.
2. Technology Review
Quantitative electroencephalograph (QEEG) monitoring is a valuable non-invasive tool for monitoring brain activity and detecting numerous forms of neuropathological activity such as seizure and stroke. However, traditional QEEG monitoring techniques focus on the subject's brain as a whole, looking at cortical/brain activity. While this type of monitoring is very useful and even necessary to detect certain neuropathological activity or for certain procedures, such as measuring subject status with respect to sedation or anesthesia or reaction to noxious stimulation such as surgical stimulation, detecting seizures during the monitoring procedure, or detecting brain damage, it cannot always detect other problems or conditions that may arise or exist within one particular brain hemisphere or as a function of the communication between the two brain hemispheres.
These problems may include varying levels of sedation between hemispheres; seizure or stroke related to one side of the brain; or other neuropathological problems. While bilateral brain monitoring methods have been proposed and even utilized for basic monitoring of a subject's two brain hemispheres individually and simultaneously, the focus of such existing methods has been solely based on the patient's state of consciousness by means of brain/cortical activity and this activity circuitously is based on the whole brain rather than the activity of each hemisphere. These methods have ignored the potential for essentially real-time detection of presently occurring neuropathological activity or of the diagnosis or identification and location of such past neuropathological activity particularly where the differences between hemispheric activity is indicative of such problems.
It is therefore an object of the present invention to provide a device, system, monitor and method that meets all of these needs and others where such a device and method is applicable. It is another object of the present invention that this device and method accurately detect and display information simultaneously regarding a subject's brain activity or cortical state and potential neuropathological activity for both hemispheres of the subject's brain. It is still another object of the present invention that this device and method be usable by technicians, clinicians, caregivers, emergency response technicians, or anyone else with appropriate specialized medical training to monitor a subject's brain or cortical activity as well as by such persons with little specialized training but in the position to monitor a subject for neuropathological activity that may occur. Finally, it is an object of the present invention that this device that a patient's diagnosis and therapeutic treatment be more accurately determined based on the better diagnostic data from the testing and monitoring of the patient.